The present invention relates to methods, apparatuses, materials and systems for the repair of musculoskeletal injury, and in particular, for bone and cartilage repair and replacement.
In another aspect, the invention relates to polymeric compositions, and to minimally invasive methods and materials for the preparation of prosthetic implants and the replacement or repair of joints and joint surfaces within the body. In another aspect the invention relates to in situ curable compositions, such as polymer compositions, useful for such purposes.
In yet another aspect, the present invention relates to medical prostheses for use in in vivo applications, to methods of preparing and delivering such prostheses, and to materials useful for fabricating or preparing prostheses. In a further aspect, the invention relates to the preparation of prostheses in situ.
The musculoskeletal system is subject to injury caused by traumatic events as well as by a number of diseases, such as osteoarthritis and rheumatoid arthritis.
Repair of connective tissue of the musculoskeletal system is commonly performed using materials such as natural or synthetic tendons and ligaments. Joint repair and replacement is typically accomplished using metal and/or polymeric implants and devices. Such devices are typically fixated into existing bone by means of bone plates, adhesives, screws, and the like.
The joints of the body can be classified as between those that provide immovable articulations (synarthroidal), mixed articulations (amphiarthroidal), and movable articulations (diarthroidal). The ability of amphiarthroidal and diarthroidal joints to provide effective and pain-free articulation, and/or to serve their weight-bearing function, is generally dependent on the presence of intact, healthy cartilage (e.g., fibrocartilage or hyaline cartilage) within the joint.
Total joint replacement is indicated under conditions in which the cartilage surface between the bones forming a joint has degenerated. Often it has degenerated to a point where there is significant pain during locomotion, as well as during translation and rotation of joint components. Such degenerative joint disease is commonly treated by a technique known as total joint replacement arthroplasty, which is typically an invasive procedure that involves replacement of the original surfaces with artificial weight bearing materials in the form of implants.
Hip replacement generally involves the implantation of a femoral component in the form of a ball mounted on a shaft, together with an acetabular component in the form of a socket into which the ball sits.
Total knee replacement is somewhat more difficult than hip replacement because of the complex loading pattern of the knee. The tibial component of a total knee replacement is fixed in the cancellous bone of the tibia. The femoral component is typically fixed to the cortical bone of the femoral shaft using a suitable cement.
The tibial portion of a knee prosthetic device generally involves the insertion of a broad plateau region covering the tibia, after bone of the subchondral plate is removed. In most designs, a composite material is provided, involving a metal support underlying a polymeric, or fiber-reinforced polymeric tray.
A wide array of materials have been described for use in the manufacture of medical implants. See generally, Chapter 1, in Biomaterials, Medical Devices and Tissue Engineering: An Integrated Approach, Frederick H. Silver, ed., Chapman and Hall, 1994. Such materials generally fall into the categories of metals, polymers, ceramics, and composite materials.
A recent article entitled xe2x80x9cNew Challenges in Biomaterialsxe2x80x9d, Science, 263:1715-1720 (1994), Peppas et al., provides a useful overview of the current state of the art in biomaterials. The article describes a number of materials currently used for orthopedic applications, including metals (iron, cobalt, and titanium), degradable polymers, self-reinforced compositions of polyglycolic acid, stronger polymers such as polydioxanone, and ceramic materials such as hydroxyapatite and certain glasses.
Elsewhere, for instance at page 1719, the Peppas et al. article refers to the potential usefulness of polymers that can be triggered to undergo a phase change. The article itself does not identify such polymers, but instead postulates that materials that are initially liquid might be administered through a minimally invasive surgical device and then triggered to solidify or gel in the presence of ultraviolet light, visible light, or ionic change in vivo. As an example of this approach the article cites an article of Hill-West, et al., Obstet. Gynecol. 83(1):59-64 (1994).
The Hill-West et al. article, in turn, describes the use of a conformable, resorbable hydrogel barrier for preventing postoperative adhesions in animals. The article describes the formation of the hydrogel barrier in situ by photopolymerizing a solution of a macromolecular prepolymer using UV light. The hydrogel barrier is not described as being useful in weightbearing, orthopedic applications, and in fact, was completely resorbed within 7 days after application.
There are a number of drawbacks associated with the biomaterials and related methods presently employed for orthopedic applications, and in particular joint repair and replacement. One such drawback is that these methods generally involve invasive surgery, i.e., resecting tissue in order to gain access to the injury site. In turn, invasive surgery typically involves up to 7 to 10 days of hospitalization, with the costs associated therewith.
A related drawback of an arthrotomy involves the need to cut through skin, nerves, vessels, muscles, ligaments, tendons, and/or joint capsules. Certain procedures can also require the use of either general or spinal anesthesia. They may also require blood transfusions and significant recovery time accompanied by post-surgical pain and discomfort. Lastly, prolonged physical therapy is typically required to strengthen operative areas and prevent contractures. Such therapy can often last up to six weeks or more.
It would be particularly useful to be able to repair such injuries in a manner that avoided such invasive surgical procedures and the problems associated therewith.
A number of approaches, and in turn compositions, are currently employed for such purposes as preparing prosthetic implants and repairing damaged joints and joint cartilage. Such approaches include the widespread use of artificial prosthetic implants that can be formed of an array of materials such as metals, ceramics, and bioerodible or resorbable materials. Indeed, the manufacture and use of such implants has grown exponentially in recent decades. See, for instance, xe2x80x9cNew Challenges in Biomaterialsxe2x80x9d, Science, 263:1715-1720 (1994), Peppas et al.
Similarly, a number of references, and particularly those in the dental area, have described methods or apparatuses for the delivery and cure of materials within the oral cavity. Outside of the dental area, however, the number of such applications is far more limited, and includes such references as Perkins et al. (U.S. Pat No. 4,446,578) and Oechsle III (U.S. Pat. No. 4,570,270 polyurethanes as luting agents for filling cavities in bones). See also, Kuslich (U.S. Pat. No. 5,571,189 expandable fabric spine implant device in combination with a xe2x80x98graft mediumxe2x80x99 to promote fibrous union of joints); Parsons et al. (U.S. Pat. No. 5,545,229 intervertebral disc spacer formed of an elastomeric material in nucleus and annulus); Porter et al. (U.S. Pat. No. 5,591,199 curable fiber composite stent, fibrous material treated with curable material to form curable fiber composite); Glastra (U.S. Pat. No. 5,529,653 expandable double walled sleeve, space filled with curable material; and Cowan (U.S. Pat. No. 5,334,201 vascular reinforcing stent having tubular sleeve of a cross-linkable substance, the sleeve being encapsulated within a biocompatible film).
Even more recently, Applicant""s U.S. Pat. No. 5,556,429 describes a joint resurfacing system which, in a preferred embodiment, involves the use of minimally invasive means to access and prepare a joint site, such as a knee, and to deliver a curable biomaterial to the prepared site and cure the biomaterial in apposition to the prepared site. The system includes the use of curable biomaterials such as silicone polymers and polyurethane polymers.
Polyurethanes themselves have been developed and used since at least the 1940""s for the preparation of a variety of materials, including cast polyurethane rubbers and millable gums. Cast polyurethane rubbers can be subdivided into four general groups, including 1) unstable prepolymer systems, 2) stable prepolymer systems, 3) quasi-prepolymer systems, and 4) xe2x80x9coneshotxe2x80x9d systems. See, for instance, xe2x80x9cPolyurethanes and Polyisocanuratesxe2x80x9d, Chapter 27 in Plastics Materials, J. Brydson, ed., 6th ed. Butterworth Heeinemann (1995).
Generally, such compositions involve the reaction of a polyhydroxy material (polyol) with an isocyanate to provide a polyurethane material. A limited number of references describe the use of components such as hydroxyl-terminated butadiene in the context of a polyurethane. Khalil, et al. (U.S. Pat. No. 5,288,797), for instance, describe moisture curable polyurethane adhesive compositions in the form of a blend of polyurethane prepolymers, together with additives (such as carbon black) and a resin, which are used to improve mechanical properties such as sag resistance. The list of polyols described as being useful for forming the prepolymer is said to include polybutadiene having at least two terminal primary and/or secondary hydroxyl groups.
Similarly, Graham et al. (U.S. Pat. No. 4,098,626) describes a hydroxy terminated polybutadiene baspolyurethane bound propellant grains, while Chapin et al. (U.S. Pat. No. 4,594,380) describe an elastomeric controlled release article having a matrix formed of a polyurethane that itself is the reaction product of an isocyanate and a polyol selected from a group that includes hydroxyl-terminated polybutadiene.
While materials such as those described above are useful for their intended purposes, and have created new opportunities in their respective fields, it would be desirable to further improve various properties associated with such materials. With regard to their use as in vivo curable biomaterials, for instance, certain polyurethane compositions have been found to produce undesirable bubbles when delivered and cured in the presence of moisture. Improvement of this and other properties would be highly desirable, provided such improvement can be accomplished without undue effect on other desired and necessary properties. It would be highly desirable to have a polyurethane composition that improves the moisture cure characteristics and other properties of such a material, without detrimental effect on other necessary and preferred properties.
The development of implantable medical devices has grown dramatically over past decades. Correspondingly, those developing new and useful biomaterials for use in fabricating such devices have attempted to keep pace. The implantable medical devices can themselves take a wide variety of forms and purposes.
Many prostheses are used to replace or repair orthopedic joints. The joints of the body can be classified as between those that provide immovable articulations (synarthroidal), mixed articulations (amphiarthroidal), and movable articulations (diarthroidal). The ability of amphiarthroidal and diarthroidal joints to provide effective and pain-free articulation, and/or to serve their weight-bearing function, is generally dependent on the presence of intact, healthy cartilage within the joint.
Conventional joint prostheses are generally fabricated by the manufacturer, often as component parts of varying sizes, and selected and implanted by the surgeon in the course of invasive surgery. The applicant of the present invention, however, has demonstrated the manner in which curable biomaterials can be used to repair or resurface a joint. See, for instance, U.S. Pat. No. 5,556,429. This patent describes, for instance, the use of minimally invasive means to deliver and cure a biomaterial at a prepared site such as the knee, as well as the optional use of holes drilled into the bone, e.g., subchondral bone, that can be filled with the biomaterial to provide anchor points once cured.
The delivery of such biomaterials can take the shape of the prepared site, or can further incorporate the use of a mold, e.g., in the manner described in Applicant""s corresponding PCT Patent Application No. PCT/US97/00457. In one such embodiment, for instance, a mold is provided in the form of a balloon that can be delivered to the site of an intervertebral disc space, and there filled with biomaterial in order to serve as a replacement disc.
Other examples of implanted or implantable devices include Kuslich (U.S. Pat. No. 5,571,189); Kuslich (U.S. Pat. No. 5,549,679); Parsons et al. (U.S. Pat. No. 5,545,229); Oka (U.S. Pat. No. 5,458,643); Baumgartner (U.S. Pat. 5,171,280); Frey et al. (U.S. Pat. No. 4,932,969); Ray et al. (U.S. Pat. No. 4,904,260); Monson (U.S. Pat. No. 4,863,477); and Froning (U.S. Pat. No. 3,875,595).
Implantable medical prostheses can take other forms as well, including other traditional types that are fabricated and packaged prior to use, and implanted in either a transitory, temporary or permanent fashion within the body. Such prostheses can be used, for instance, as or in connection with passageways within the body such as catheters, such as stents and shunts. Other examples of devices implantable on at least a transitory basis include catheters such as balloon catheters. See, for example, the following U.S. Patents to Walinsky (U.S. Pat. No. 5,470,314); Saab (U.S. Pat. No. 5,411,477); Shonk (U.S. Pat. No. 5,342,305); Trotta et al. (U.S. Pat. No. 5,290,306); Tower (U.S. Pat. No. 4,913,701); Oechsle III (U.S. Pat. No. 4,570,270); and Perkins et al. (U.S. Pat. No. 4,446,578).
The use of stents, in particular, has become accepted as a means for preventing abrupt vessel closure and restenosis following balloon angioplasty and over the past decade has grown dramatically as problems inherent in early designs have been overcome. Typically, stents are constructed from nonthrombogenic materials of sufficient flexibility (in their unexpanded state) to allow passage through guiding catheters and tortuous vessels. Such stents are typically radiopaque to allow fluoroscopic visualization. To date, most coronary stents have been constructed from either stainless steel or titanium, e.g., in the form of an expandable mesh, wire coil, slotted tube, or zigzag design.
Recent developments have included the use of balloon-expandable stents. Such stents are available in a number of configurations, such as the Gianturco-Roubin Flex-Stent (Cook, Inc.), the Palmax-Schatz Coronary Stent (Johnson and Johnson), Wiktor Stent (Medtronic, Inc.), Strecker Stent (Boston Scientific), ACS Multi Link Stent (Advanced Cardiovascular Systems, Inc.) the AVE Micro Stent (Applied Vascular Engineering) and Cordis Stent (Cordis Corp.). Even more recently, temporary stents (e.g., removable or biodegradable) have been developed, in an effort to achieve the structural support and lumen stabilizing benefits of permanent stenting without the problem of thrombosis.
Most stents, and certainly most, if not all, commercially available stents, are manufactured and sterilized by the manufacturer, and provided in an insertable form. Other approaches have been described, however, including modification of the stent material either pre-or post-delivery. See, e.g., Porter et al., U.S. Pat. No. 5,591,199 (for a xe2x80x9cCurable Fiber Composite Stent and Delivery Systemxe2x80x9d). In spite of recent accomplishments, many stents available today continue to encounter problems upon insertion (e.g., lack of flexibility) and/or over the course of their use (e.g., erosion, tissue incompatability).
In a similar manner, a variety of preformed catheters and shunts have been developed in the form of tubular instruments to allow passage of fluid from, into, or between body cavities. Relatively few of the many known catheters are formed or prepared in situ. Recent patents of Glastra (U.S. Pat. Nos. 5,344,444 and 5,529,653) describe, for instance, a method for the fabrication and use of an expandable hollow sleeve for local support or reinforcement of a body vessel. The hollow sleeve is described as having a curable material, such as an xe2x80x9cacrylatexe2x80x9d, contained within an absorbent material within the sleeve. In a different approach, Cowan (U.S. Pat. No. 5,334,201) describes a stent made of a crosslinkable material, by a method that involves encapsulating an uncured stent in a biologically compatible film, transluminally inserting the stent/film into position, and curing the stent.
Preformed catheters and grafts have also been used in the treatment of abdominal aortic aneurysms. The ultimate goal in the treatment of aortic aneurysms is to exclude the aneurysm from the aortic bloodstream without interfering with limb and organ perfusion. Direct surgical repair of such aneurysms is associated with high morbidity and mortality. The technique of placing a prosthetic graft into the opened aneurysm and suturing it to xe2x80x9cnormalxe2x80x9d aorta above and below requires extensive intraabdominal or retroperitoneal dissection, as well as interruption of blood flow during completion of the anastomoses, under general anesthesia.
Methods and materials used to prepare implantable prostheses, as described above, can be contrasted to those used in the burgeoning dental field, in which polymers play an important role as ingredients of composite restorative materials, cements and adhesives, cavity liners and protective sealants. See, for instance, Brauer and Antonucci, xe2x80x9cDental Applicationsxe2x80x9d pp 257-258 in Concise Encyclopedia of Polymer Science and Engineering. 
At times, the preparation of such dental prostheses relies on the use of molds taken of parts of the body in order to then cast or otherwise form prosthetic replacement parts. See, for instance, Weissman, U.S. Pat. No. 4,368,040 for xe2x80x9cDental impression tray for forming a dental prosthesis in situxe2x80x9d. See also, xe2x80x9cProcess for making a prosthetic implantxe2x80x9d, Kaye U.S. Pat. No. 5,156,777, which involves the use of three-dimensional data to prepare a life size model of an organ site, which in turn is used to cast a prosthetic implant.
Clearly the ability to mold body parts, such as teeth, in order to form prosthetic devices is considerably different than the preparation and delivery of preformed implants themselves, particularly for implants used in internal sites or tissues that are not as readily accessible as the oral cavity. Among the several distinctions between preformed implantable prostheses and those formed in situ are the fact that the latter are typically restricted to external or surgically accessible sites or tissues. In these situations, the ability to deliver a material used to form a prosthesis at an accessible site, although certainly demanding in many respects, has far fewer considerations than a material intended for delivery and use internally.
A number of problems that continue to affect the further development of some or all of the above-described implanted prostheses, include problems that affect the preparation of the prostheses themselves, their delivery to the site of use, and their interactions with the host or surrounding tissue in the course of their use.
For example, the physician cannot correct the size and shape of the prostheses once it has been introduced to the body; therefore, all measurements and adjustments of size must be made preoperatively. In the case of aortic grafts, the aorta may continue to enlarge and thus pull away from the fixation stent. Problems associated with the healing interface between the stent, the graft, and the aorta is not known, and the graft may dislodge and migrate, causing acute iliac occlusion. The aneurysm may continue to function despite an intact functioning endovascular graft.
It would clearly be desirable to have a system that permits prostheses to be prepared and used in a manner that overcomes some or all of these concerns.
The present invention overcomes the drawbacks associated with the prior art by providing a method, and related composition and apparatus for repairing or resurfacing the site of injured tissue by minimally-invasive means.
In one embodiment, the method of the present invention comprises the steps of:
(a) providing a curable biomaterial; and
(b) employing minimally invasive means to:
(i) prepare the tissue injury site for receipt of the biomaterial;
(ii) deliver a quantity of the curable biomaterial to the prepared tissue injury site;
(iii) cure the delivered biomaterial in such a manner that the cured biomaterial is permanently retained in apposition to the prepared site; and
(iv) contour the cured, retained biomaterial to achieve a desired conformation approximating that of natural tissue.
The method of the invention lends itself to a corresponding system that comprises curable biomaterial, in combination with minimally invasive means for preparing the tissue site; delivering the biomaterial to the prepared tissue site; curing the biomaterial in situ; and contouring the cured biomaterial. The individual components of such a system, and particularly means for delivering and curing biomaterial in a minimally invasive fashion are considered novel as well.
In a preferred embodiment, a system is provided that comprises: (a) an arthroscopic surgical instrument; and (b) a fluid delivery cannula capable of delivering a flowable, curable biomaterial under arthroscopic visualization, the biomaterial comprising a curable polymer and hydrogel.
The preferred system can be used to perform a method that comprises the steps of:
(a) providing a flowable, curable biomaterial comprising a curable biomaterial;
(b) preparing the tissue injury site by operation of the arthroscopic instrument, and under arthroscopic visualization;
(c) preparing a tissue access site to include anchor points in the subchondral bone and inserting and directing the delivery cannula through the tissue access site to the site of tissue injury;
(d) delivering a quantity of the curable biomaterial through the cannula to the prepared site;
(e) curing the delivered biomaterial by minimally invasive means and in a manner such that the cured biomaterial is retained in apposition to the prepared site; and
(f) contouring the cured biomaterial to achieve a desired conformation approximating that of natural tissue.
In an alternative embodiment, the cured, shaped biomaterial can be treated or modified in order to improve one or more desirable properties, for instance, it can be coated with a permanent interface material in order to improve the biocompatibility or coefficient of friction of the final implant.
In another aspect, the present invention provides a curable polyurethane composition comprising a plurality of parts capable of being sterilized, stably stored, and mixed at the time of use in order to provide a flowable composition and initiate cure, the parts including: (1) a quasiprepolymer component comprising the reaction product of one or more polyether polyols, one or more isocyanates, and one or more reactive hydrophobic additives, and (2) a curative component comprising one or more polyether polyols, one or more chain extenders, one or more catalysts, and optionally, other ingredients such as an antioxidant and dye. Upon mixing, the composition is sufficiently flowable to permit it to be delivered to the body by minimally invasive means, and there fully cured under physiologically acceptable conditions. Preferably, the component parts are themselves flowable, or can be rendered flowable, in order to facilitate their mixing and use.
Applicants have discovered, inter alia, that the presence of the reactive hydrophobic additive of the prepolymer provides several unexpected and desirable features, both in the formulation and use of the prepolymer itself, as well as in the mixed composition. These features include an improved combination of such properties as moisture cure characteristics, crosslinking, viscosity, compression fatigue, and stability. In particular, the use of the polymer significantly lessens, and can avoid altogether, the appearance of bubbles seen previously with polyurethane compositions cured in vivo in the presence of moisture. While not intending to be bound by theory, it appears that the presence of a sufficient amount of hydrophobic or nonpolar additive, and particularly one that is miscible with the polyether component, alters or affects the surface tension (e.g., as determined by the contact angle) of the resulting composition, and in turn, permits the composition to cure with a significant reduction in the appearance of bubbles. Surprisingly, this and other improved characteristics are not achieved at the sacrifice of other desirable properties.
In a preferred embodiment, within the prepolymer, the polyether component is present at a concentration of between about 2% and about 10%, and preferably between about 4% and about 8% by weight, based on the weight of the composition, and is selected from the group consisting of linear or branched polyols with polyether backbones of polyoxyethylene, polyoxypropylene, and polytetramethylene oxide (polyoxytetramethylene), and copolymers thereof. A particularly preferred polyol is polytetramethylene oxide, preferably of relatively low molecular weights in the range of 250 to 2900, and combinations thereof.
In a further preferred embodiment the isocyanate is present in excess in the prepolymer component, e.g., at a concentration of between about 30% and about 50%, and preferably between about 35% and about 45%, by weight. The isocyanate is preferably an aromatic (poly)isocyanate selected from the group consisting of 2,2xe2x80x2-, 2,4xe2x80x2-, and 4,4xe2x80x2-diphenylmethanediisocyanate (MDI), and combinations thereof.
In such an embodiment, the reactive polymer additive itself is present at a concentration of between about 1% and about 50% by weight, and is selected from the group consisting of hydroxyl- or amine-terminated compounds selected from the group consisting of poybutadiene, polyisoprene, polyisobutylene, silicones, polyethylenepropylenediene, copolymers of butadiene with acryolnitrile, copolymers of butadiene with styrene, copolymers of isoprene with acrylonitrile, copolymers of isoprene with styrene, and mixtures of the above. In a particularly preferred embodiment the additive comprises hydroxyl-terminated polybutadiene, present at a concentration of between about 5% and about 30%, by weight, and preferably between about 5% and about 20% by weight.
In a further preferred embodiment, the polyether polyol of the curative component is as described above with regard to the prepolymer and is present at a final concentration of between about 20% and 60%, and preferably between about 30% and about 45%, by weight. In such an embodiment, the chain extender comprises a combination of linear (e.g., cyclohexane dimethanol (xe2x80x9cCHDMxe2x80x9d)) and branched (e.g, trimethyloyl propane (xe2x80x9cTMPxe2x80x9d) chain extenders, with the former being present at a final concentration of between about 1% and 20% (and preferably between about 5% and about 15%), and the latter being present at a final concentration of between about 1% and about 20%, and preferably between about 1% and about 10%, by weight of the final composition.
Surprisingly, the composition provides improved properties, including an improved combination of such properties as hardness, strength and/or cure characteristics (particularly in the presence of moisture), as compared to compositions previously known. More surprisingly, Applicants have discovered that such improvement can be achieved without detrimental effect on other desired properties, including those that arise (a) prior to delivery, (b) in the course of delivery (including whatever mixing, curing, and/or shaping that may occur), and finally, (c) following cure and in the course of extended use in the body.
In another aspect, the invention provides a cured composition, prepared as the reaction product of a plurality of parts as described herein. In yet another aspect, the invention provides a kit that can be used to prepare a composition and/or that itself includes a composition as a component part. A kit, for instance, may take the form of a composition (or its components) in combination with pre-formed device components or accessories, such as an implantable mold apparatus for shaping and restraining the composition. Optionally, a kit can also include a composition (or its components or parts) in combination with a delivery device adapted to deliver the composition to the site of tissue injury. Optionally, a kit may also take the form of a composition, either as its component parts and/or in combination with other ingredients or materials, such as a filler or hydrogel (used to form a matrix), or together with an implantable prosthetic device. In any such kit, it is envisioned that a kit may include one or more protocols or instructions for use.
In yet another aspect, the invention provides a method of preparing and a method of using such a composition. In a further aspect, the invention provides a cured composition (optionally within a mold apparatus), for use in apposition to a joint surface, as well as the combination of such a joint surface with a cured composition (optionally within a mold apparatus) in apposition thereto.
In yet another aspect, the present invention provides an apparatus and method for forming a prosthesis, in situ, the method, in a preferred embodiment, comprising the steps of:
a) providing an implantable mold apparatus comprising a cavity adapted to receive and contain a flowable biomaterial and a conduit adapted to connect the cavity to a source of curable, flowable biomaterial,
b) inserting the mold, preferably by minimally invasive means, to a desired site within the body,
c) delivering biomaterial to the mold in order to fill the cavity to a desired extent,
d) permitting the biomaterial to cure to a desired extent, and
e) employing the molded biomaterial in situ as a prosthetic device.
The apparatus, in turn, provides an implantable mold apparatus comprising an expandable cavity adapted to receive and contain a flowable biomaterial in a geometry, configuration and/or position optimal for the intended purpose, and a conduit adapted to connect the cavity to a source of curable, flowable biomaterial. The conduit is preferably removable from the filled cavity, e.g., by cutting it at or near the point where it joins the cavity. Optionally, and preferably, the apparatus further includes means for providing positive or negative air pressure within or to the biomaterial cavity, in order to facilitate the delivery of biomaterial and/or to affect the final shape of the cured mold.
The apparatus and method can be used for a variety of applications, including for instance, to provide a balloon-like mold for use preparing a solid or intact prosthesis, e.g., for use in articulating joint repair or replacement and intervertebral disc repair. Alternatively, the method can be used to provide a hollow mold, such as a sleeve-like tubular mold for use in preparing implanted passageways, e.g., in the form of catheters, such as stents, shunts, or grafts.
In yet another aspect, the invention provides a mold apparatus useful for performing a method of the invention, e.g., in the form of an inflatable balloon or tubular mold, preferably in combination with the conduit used to deliver biomaterial. Along these lines, the invention further provides a system useful at the time of surgery to prepare an implanted prosthesis in vivo, the system comprising a mold apparatus (e.g., cavity and conduit) in combination with a supply of curable biomaterial, and optionally, with a source of positive and/or negative air pressure.
In a further aspect, the invention provides a corresponding prosthesis formed by a method of the present invention, including for instance, an implanted knee prosthesis, intervertebral disc prosthesis, and a tubular prosthesis for use as a catheter, such as a stent, shunt, or graft (e.g., vascular graft). The present invention further provides surgical kits that include a mold apparatus as presently described, in combination with a corresponding drilling template, and a kit in which a mold apparatus is provided in combination with a supply (e.g., sufficient for a single use) of biomaterial itself.